Window's Vista requirements come into view

When Windows Vista arrives, will you get a first or business class seat, or will you be relegated to economy?

The next version of Microsoft Windows, due to reach consumers in January, comes in a variety of flavours, and the Starter and Home Basic editions don't include the new Aero Glass interface, which provides extra features such as live thumbnail screens that pop up from the taskbar, and Flip 3D, a three-dimensional view. Arvind Mishra, a senior product manager with Microsoft in Redmond, says: "We think [Aero] is a higher value feature, so it should be in a higher value product."

Last week, Microsoft finally provided more details of the kind of PC required to run Windows, and released a beta version of its Windows Vista Upgrade Advisor. XP users can download and run this software to find out if their systems are up to scratch.

The Basic version of Vista does not require a powerful PC. Microsoft reckons it will run with an 800MHz processor, 512MB of memory and a 20GB hard drive with 15GB free. This counts as a Windows Vista Capable PC, and new machines that meet this spec can carry a sticker that says so.

However, the Aero user interface - included in the Home Premium, Business and Ultimate editions - requires 3D graphics hardware. Technically, the graphics system should have 128MB of memory, Pixel Shader 2.0 hardware and support for WDDM graphics drivers. Any PC that runs games using DirectX 9 should be OK. Microsoft also recommends at least a 1GHz processor, 1GB of memory, and a 40GB hard drive with 15GB free. A new PC that can run Aero qualifies for a Windows Vista Premium Ready sticker.

With Aero, the user interface is handled by the graphics processor, not by the CPU, as it is with XP and Vista Basic. Using the GPU also means an Aero version runs faster than a Basic system, and is also less likely to suffer visual glitches or crashes. Mishra says that "20 to 30% of blue screen crashes are actually due to graphics drivers."

Vista also has a fourth option: Windows Classic. This has much the same appearance as Windows 2000. Many companies are still running that version, and the Classic mode allows them to keep a similar interface across all their PCs, and put off the cost of retraining their users.

Running the Vista Upgrade Advisor is the simplest way to find out if a PC can run Aero, and Microsoft thinks most PCs released in the past year should be able to. With notebook PCs without a graphics card, it may mean increasing the amount of main memory devoted to the screen display.

But previous launches of Windows have shown that very few users ever upgrade their operating system. The vast majority only switch when they buy a new PC.

And since many XP users will have to upgrade their hardware to run Vista with Aero - by adding more memory and perhaps buying a new graphics card - it seems reasonable to guess that the number of upgraders will be even lower than usual.